The invention relates to a device for generating a steering signal for controlling an actuating drive for an adjustment of steerable wheels on motor vehicles, in particular passenger vehicles.
For reasons of safety and comfort, endeavors have been made for some time, apart from the actuation for the horn contact, to arrange more and more devices for actuation of the most varied of vehicle functions (lamp switches, windscreen wipers, window lifters, radio, heating, telephone) directly in the steering wheel, so that the driver is no longer forced to take one hand from the steering wheel to switch on such functions. It is immediately clear that the transmission of electrical signals generated on a rotatable steering wheel to the adjusting members fixedly arranged in the bodywork of the motor vehicle is not without problems, in particular when a plurality of different signals has to be transmitted. Therefore, already fixed or substantially fixed steering devices were proposed, in which the mechanical coupling between steering device and steering linkage has been replaced by a measurement transducer on the steering device and an actuating drive on the steering linkage. With such steering devices, one can dispense with the conventional maximum 2 to 4 revolutions to achieve the maximum steering angle of the wheels and one can limit the actual adjustment distance for the actuation of the steerable wheels to a rotation angle of 30 degrees or less. Thereby, the transmission of a plurality of signals is not a problem, because the actuating devices are either arranged on parts of the steering device which are constructed so as to be fixed relative to the bodywork, or else on parts of the steering device which are only able to be moved by a small rotation angle relative to the bodywork, so that one manages with simple lead loops in order to be able to produce an electrical connection between rotating and fixed parts.
A mechanical uncoupling and an electrical transmission of the steering command to the steerable wheels is also necessary if one wishes to achieve a driver-independent vehicle stabilizing by means of modern safety systems and in so doing also wishes to influence the adjustment angle of the steerable wheels.
The development of such steering devices is still at its beginnings and the proposals made hitherto still do not satisfy all requirements.
The invention provides a steering device which is of simple construction and which, vis-a-vis conventional steering wheels, demands from the driver only little effort to get into the way of it. This is achieved in a device which comprises a non-rotatable frame having an axis of symmetry and curved guiding portions, as well as a pair of handles intended for transmitting actuating forces and being coupled with each other. The handles are mounted on the guiding portions so as to be displaceable in same direction and are able to be displaced along the guiding portions and relative to the axis of symmetry to a limited extent. The device further comprises a measurement transducer for generating one of an electrical and electronic signal for determining a position of the handles relative to the frame.
The proposed steering device has the advantage that it can readily take the place of conventional steering wheels, without the driver having to assume a completely different steering-and sitting position. The steering commands are also introduced through an accustomed movement of the handles which are coupled with each other, and owing to the comparatively short adjustment distance, no alteration of the position of the hands is necessary as in conventional steering wheels, which is to be regarded as advantageous with regard to safety and comfort.